Low-loss transmission line structure comprising a dielectric layer stacked with conductive layers having signal strips and ground strips and including air grooves close to the signal strips

Abstract

The disclosure discloses a low-loss transmission line structure, which belongs to the field of radio frequency transmission lines and includes at least two metal layers stacked in a vertical manner. A dielectric layer is filled between the metal layers. The metal layers include a signal transmission strip in a middle portion. Ground strips are provided on both sides of the signal transmission strip. Through holes are evenly distributed on the dielectric layer, and the signal transmission strips on each of the metal layers are connected through the through holes to form a signal transmission line. The ground strips on each metal layer are connected through the through holes.

What is claimed is: 
     
       1. A low-loss transmission line structure, comprising:
 at least two metal layers, stacked in a vertical manner and spaced apart from each other, wherein a middle portion of each of the at least two metal layers serves as a signal transmission strip, the respective signal transmission strip is disposed to transmit an electromagnetic wave signal, remaining portions of the at least two metal layers on both sides of the respective signal transmission strip serve as ground strips, the respective ground strips and the respective signal transmission strip are spaced apart; and 
 at least one dielectric layer, is disposed between the at least two metal layers, the dielectric layer is provided with through holes, the respective signal transmission strips on each of the at least two metal layers are connected by the through holes to form a signal transmission line, and the respective ground strips on each of the at least two metal layers are connected by the through holes, and the low-loss transmission line structure is able to allow most of an electromagnetic field around the low-loss transmission line structure to exist in air, thereby effectively reducing a loss during a signal transmission, the through holes do not penetrate the respective signal transmission strip and the respective ground strips, wherein air grooves are evenly distributed in the dielectric layer close to the respective signal transmission strip. 
 
     
     
       2. The low-loss transmission line structure according to  claim 1 , wherein the respective ground strips on an uppermost one of the at least two metal layers are connected to each other through a low-loss connection structure, and the low-loss connection structure is at least one metal jumper or a gold-wire bonding wire. 
     
     
       3. The low-loss transmission line structure according to  claim 2 , wherein the at least one metal jumper is connected to each other to form a metal shield. 
     
     
       4. The low-loss transmission line structure according to  claim 3 , wherein the respective ground strips on the uppermost one of the at least two metal layers and the respective ground strips on a lowermost one of the at least two metal layers are connected to each other through the metal shield. 
     
     
       5. The low-loss transmission line structure according to  claim 1 , wherein the air grooves are through grooves that penetrate upper and lower surfaces of the dielectric layer. 
     
     
       6. The low-loss transmission line structure according to  claim 1 , wherein a shape of the air groove is circular or polygonal. 
     
     
       7. The low-loss transmission line structure according to  claim 1 , wherein the dielectric layer is made of an epoxy glass fiber cloth substrate, or a dielectric plate whose surface is able to be printed with metal, or a low-loss microwave dielectric plate. 
     
     
       8. The low-loss transmission line structure according to  claim 1 , wherein the low-loss transmission line structure is applied in a dielectric integrated suspension line structure, the ground strips are multiple ground metal layers respectively disposed on a uppermost one of the at least two metal layers and a lowermost one of the at least two metal layers in the stacked manner and spaced apart from each other, the at least one dielectric layer is disposed between the multiple ground metal layers which are spaced apart from each other in the stacked manner, and the multiple ground metal layers are connected through the through holes.